ISSN:0010-3624    

DOI:10.1080/00103629809369985

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Nine surface soil acidification treatments were tested to determine which were effective in preventing the development of chlorosis in white oak seedlings. The treatments were applied with and without subsurface sulfuric acid to white oak seedlings purposely planted in calcareous soil. Nutrient imbalances as compared to healthy seedlings consisted of low foliar nitrogen, phosphorus, zinc, iron, and copper for uniformly chlorotic seedlings. Interveinally chlorotic seedlings exhibited low nitrogen and iron and high potassium. Miracid, Hi‐Acid, and ammonium sulfate surface treatments were highly effective in preventing chlorosis provided that subsurface treatment was omitted. Except when applied with H2SO4, A12SO4, and granular sulfur surface treatments, subsurface H2SO4had an adverse effect on treatment success.

ISSN:0010-3624    

DOI:10.1080/00103629809369986

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Chemical analysis of plants is often done without paying attention to the ubiquitous natural presence of exogenous material on the plant surface. The analytical result will then be higher than the endogenous plant concentration. It is shown that this error can be related to three parameters: (i) the surface loading L, (ii) the enrichment factor (EF) of the exogenous material with respect to the soil, and (iii) the plant‐to‐soil concentration ratio (CR). These factors are considered for 19 essential and trace elements and the results indicate that the error can range from insignificant to disastrous. Experimental data are mostly for needles of spruce trees growing in a relatively clean surrounding, but the proposed relations can be extended to estimate the effect for other plant species and surroundings.

ISSN:0010-3624    

DOI:10.1080/00103629809369987

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Six‐month‐old coffee plants were grown in the greenhouse in pots containing a Dark Red Latosol (Orthox), to study the effect of boron (B) and zinc (Zn) on growth and leaf content of these micronutrients. Boron was added at levels of 0, 1, 3, and 5 mg kg‐1, whereas Zn was added in proportions of 0, 5, 10, and 20 mg kg‐1. Boron application affected total dry matter, height and diameter of stem, length and number of plagiotropic branches, number of leaves, ratio between total leaf area and number of leaves (ULA), ratio between total leaf area and total dry matter (LAR), leaf moisture, and index of potential yield (IPY). The IPY, defined as the ratio of dry matter of developed flowering buds plus flowers to the dry matter of underdeveloped flower buds and flowers, proved to be the an excellent parameter to assess B levels. Leaf B, well correlated with IPY, varied from 50 to 60 mg kg‐1. Available B in soils, in nig kg‐1, ranged from (with the critical levels between parentheses): 0.2 to 0.3 (0.2), as determined in a saturation paste, 0.6 to 1.0 (0.9), as determined in a hot water extract, 0.9 to 1.3 (1.2), with monocalcium phosphate in acetic acid, 1.1 to 1.4 (1.3), by Mehlich 1 method, 2.1 to 2.4 (2.4), by 0.05N HC1, 2.2 to 2.4 (2.4), by 0.1N HCl. Zinc additions caused a decrease in growth when B supply was limiting. On the other hand, B had no effect on dry matter yield when Zn was not added. Adequate Zn soil levels in mg kg‐1were 4.4, as determined by 0.05N HCl extraction, 4.2, by 0.1N HC1, 3.9, by Mehlich 1, 2.7, by EDTA extraction, and 2.1, in DTPA extracts. Leaf Zn, not affected by Zn additions, was between 12–14 mg kg‐1.

ISSN:0010-3624    

DOI:10.1080/00103629809369988

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This work investigated the kinetics of carbon (C) mineralization when different doses of organic materials with varying degrees of stability were added to an arid soil. Respiration assays showed that the incorporation of wastes led to a greater emission of carbon in the form of CO2and greater degree of microbial activity than those occurring in the control soil. Soils treated with fresh waste (municipal solid waste and sewage sludge) gave off more CO2than that treated with compost, with higher values being obtained at high than at low doses. Carbon dioxide emission was reduced with the length of time the organic materials remained in the soil. The data of cumulative CO2were fitted to the equation C=C0(1‐e‐Kt)+C1. The parameters derived from this model were used as indices of organic matter decomposition, because the product of C0and K was more precise than either value separately. In all cases, an initial rapid phase of mineralization was clearly differentiated from a second slower phase.

ISSN:0010-3624    

DOI:10.1080/00103629809369989

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A sequential extraction procedure is described for quantifying nine organic fractions (soluble fats, oils, and waxes; soluble carbohydrates; soluble phenolics; total hot‐water‐solubles; holocellulose; a‐cellulose; hemicellulose; lignin; and acid‐soluble carbohydrates) in highly organic soils, such asSphagnum‐derivedpeat. We present data indicating the procedure is accurate, if and only if corrections for ash concentrations of residual peat are made after each step of the extraction procedure, and with a high degree of precision (standard errors for each fraction average 4.5% of the fraction mean value).

ISSN:0010-3624    

DOI:10.1080/00103629809369990

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Laboratory bioassays were used to investigate plant growth‐regulating effects of three different experimental soil additives, designatedEXP95, W91,andZ96.A yeast growth test was used as a general assay of bioactivity, responses to soil additives were compared to those of known plant growth regulators [indoleacetic acid (IAA), gibberellic acid (GA3), and kinetin]. A corn coleoptile elongation test was used to assay for auxin‐like activity and a dwarf pea bioassay was used for gibberellin‐like activity. The three soil additives were tested at five solution concentrations ranging from 1 to 10,000 ppm (by volume). All three soil additives stimulated yeast growth, depending on the concentration of the test solutions. However, all three soil additives inhibited plant growth in the two plant bioassays. Although this study clearly demonstrated that the three soil additives had significant biological activity at very low concentrations, there was little evidence for auxin‐like or gibberellin‐like activity.

ISSN:0010-3624    

DOI:10.1080/00103629809369991

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Small grains offer a potential animal feed at a time when moisture is usually available in the Southeast. The four major winter annual small grains, barley, oats, rye, and wheat, have not been compared as potential feed sources in the same study in the past. These four small grains were harvested at six stages of growth: vegetative, boot, heading, milk, soft dough, and hard dough. Harvest dates, dry matter (DM) yield, DM yield of regrowth following initial harvest, DM concentration, and the proportions of leaf, stem and inflorescence were measured and used to evaluate the four species for silage production and grazing potential. Rye and barley reached boot prior to the suggested planting date for corn in the Piedmont of North Carolina and dry matter yields ranged from 4.72 to 6.71 Mg ha‐1and were harvested. Barley reached milk, soft dough, and hard dough earlier than the other species and was equal to or higher than the other species in proportion of DM in leaf DM yield and total DM yield in 1982 and 1983. Wheat DM yield was second to barley from heading to hard dough in 1982 and 1983. Barley DM yield was 69 to 80% of wheat from boot through soft dough in 1984.

ISSN:0010-3624    

DOI:10.1080/00103629809369992

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Four small grain species, barley, oat, rye, and wheat were harvested at six growth stages to investigate their nutritive quality as a possible replacement for corn silage. Crude protein (CP),in vitrodry matter disappearance (IVDMD), neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin contents were measured on fresh and ensiled samples. The IVDMD, an estimate of forage ruminant digestibility, of all species generally decreased from the vegetative (765–854 g kg‐1) through the milk stage (505–662 g kg‐1) and then remained unchanged or increased slightly through hard dough with the exception of oats which often decreased during later stages of growth. The IVDMD of rye was usually lower than the other species from the milk to hard dough stage. The IVDMD of barley was generally higher than the other species at the soft and hard dough stages. The NDF, ADF, and lignin fractions usually increased from the vegetative to milk stages and remained unchanged or increased slightly through the hard dough stage. The ADF and lignin are negatively associated with forage digestibility while NDF values are negatively related to dry matter intake. The ADF of rye was generally higher than the other species at the milk and soft dough stages. Rye and barley contained more lignin than the other species from the heading through hard dough stage. Crude protein content generally decreased from the vegetative through milk stages and then leveled off or decreased slightly through the hard dough stage. Crude protein of oats was lower than other species at the vegetative stage, while rye generally contained more crude protein than the other species at the vegetative and boot stages. These data in combination with forage yield data reported in an associated paper suggest that small grains can offer a nutritious source of animal feed for farmers in the southeastern United States. Rye tended to stand out among the species at the early stages of growth (vegetative to boot) as a highly digestible green chop or grazing crop that is also high in protein. Barley and wheat stand out as excellent high yielding, nutritious silage choices at the soft dough stage.

ISSN:0010-3624    

DOI:10.1080/00103629809369993

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Phosphate solubility in Andisols and Andic soils (forest and fertilized) has been studied in soil solutions at two soil:solution ratios (1:2.5 and 1:25). Forest soils approached the variscite solubility (pIAP=30.4±0.3) while fertilized soils were closer to the amosphous analog of variscite (pIAP= 29.8±0.2). In some samples, phosphorus (P) activities were consistent with simultaneous equilibrium between aluminum (Al) and iron (Fe) phosphates. The dilution ratio, DR=10(P)1:25/(P)l:25, was 10.0±0.4 for all samples. This suggests a dissolution of phosphate minerals attaining apparent saturation in 24 h. However, the high content of dissolved organic carbon and Al in aqueous extracts also pointed to the existence of soluble ternary complexes of P with Al(Fe)‐humus complexes. These results could be consistent with simultaneous control between the dissolution of variscite‐like minerals and humus‐Al(Fe)‐P associations. Nevertheless, DR seems a valuable criterion to assess soil P status, especially in fertilized soils with high active Al and Fe contents.

ISSN:0010-3624    

DOI:10.1080/00103629809369994

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor